Cryptography

The fact is there's no such thing as a perfectly, 100& secure computer system. There will always be bugs and security experts know that.

So that were System Architects employ a strategy called defense in depth, which uses many layers of varying security mechanisms to frustrate attackers.

A common reference to this is looking back at medieval times where you have a to keep safe the King of a land and it's castle. Attackers or enemies need to beat or dodge various obstacles in order to gain access to the castle and conquer it, but int this context we're talking about the most common forms of computer security called Cryptography.

Whats is Cryptography?

The word comes from the roots 'crypto' + 'graphy' which roughly translates to  = Secret Writing.

In order to make information secret you use Cipher, an algorithm that converts plain text into CipherText.

Whats is Encryption?

The process of making text secret is called Encryption and the reverse process is called Decryption.

A bit of History

Ciphers have been used long before computers showed up but by the 1900's cryptography was mechanized in the form of encryption machines  the most famous of them all was the German Enigma, used by the Nazis to encrypt their wartime communications.

The Enigma was a typewriter like machine with both a keyboard and lamp-board and above that there was three configurable rotors that were the key to the Enigma's encryption capability. 

The machine used cross-crossing wires to swap one letter of the 26 letters of the alphabet to another by using it's three rotor that feed into the next, this can be basically translated to a Substitution Cipher.

They soon discovered a fatal cryptographic weakness because it's impossible for a letter to be encrypted as itself.

Alan Turing and some of his colleagues we're able to break Enigma codes and automate the process.

Software Cryptography